Difference between switching power supply and regulated power supply
There are many types of regulated power supply, series-type regulated power supply by the power transformer, rectifier components, filter capacitors, adjusting components (adjusting tube or Sanrui regulator), reference voltage, sampling network, comparative amplification and overload or short-circuit protection and other combinations. etc.), reference voltage, sampling network, comparative amplification, as well as overload or short-circuit protection and other combinations. As the series-type regulated power supply is a linear voltage regulator circuit, and the adjustment tube in the regulator.
regulator in the regulated voltage then. Its disadvantages are large power consumption, low efficiency and small range of permissible grid fluctuations. The general series regulated power supply allows grid fluctuation range of (220±22) V. In order to reduce power consumption and improve efficiency, it is necessary to use a series regulated power supply. In order to reduce power consumption and improve efficiency, switching type regulated power supply was introduced.
A switching type regulated power supply is often called a switching power supply. It has the following.
1, switching power supply is directly rectified and filtered to adjust the grid voltage, and then regulated by the switching regulator. So there is no need for a transformer.
2, switching power supply generally use power semiconductor devices as switches, by controlling the duty cycle of the switch to adjust the output voltage. Take the power transistor (GTR) as an example. When the switching tube saturated conduction, the collector and emitter voltage drop at both ends is close to zero, and when the switching tube cut-off, its collector current is zero, so the power consumption is small and efficiency is High efficiency. Efficiency can be as high as 70% to 95%. And power consumption is small, the heat sink is also reduced.
3, switching frequency in tens of kilohertz, the use of filter capacitors and inductors with small capacity values. Therefore, the switching power supply has a light weight, small size and other characteristics.
4, due to small power consumption, low temperature rise in the machine, thus improving the stability and reliability of the machine.
Power supply has a sub-switching power supply and regulated power supply, these two kinds of power supply is different, but there are similarities.
Switching power supply is a recent universal promotion of regulated power supply, with high efficiency, wide voltage range, stable output voltage and other characteristics, now more widely used.
For example, now the computer's ATX power supply, laptop power adapter, printer power supply, mobile phone charger and so on. Regulated power supply is in the load power change, the output voltage still maintain a fixed voltage value. Switching power supply is also a regulated power supply, but the regulated power supply can not be directly called switching power supply.
Regulated power supply is the use of electronic circuit output voltage to achieve the purpose of stabilisation of the power supply, there are series-type regulated power supply, parallel-type regulated power supply, switching regulated power supply. Ordinary series regulated power supply are installed power transformer, has the advantages of stable output voltage, small ripple, but the voltage range is small, low efficiency. Shunt regulated power supply output voltage is particularly stable, but the load capacity is very poor, only in the instrument internal reference.
Switching power supply regulator tube working in the saturation and cut-off state, resulting in small heat, high efficiency (more than 75%) and eliminates the large volume of the transformer. But switching DC regulator output DC will be superimposed on the top of the larger ripple (50mv), in the output side and connected to the regulator diode can be improved, in addition to the switching tube work is to produce a large spike pulse interference, but also need to be connected to a magnetic bead in the circuit to improve. Comparatively speaking, DC regulated power supply does not have the above defects, its ripple can be done very small (15mv or less). For power efficiency and installation volume requirements of the place with switching DC regulated power supply is best, for electromagnetic interference and power purity requirements of the place (such as capacitive leakage detection) more linear DC regulated power supply. In addition, when the circuit needs to be isolated when most of the DC-DC to do the isolated part of the power supply (DC-DC from its working principle is switching DC regulated power supply). The high-frequency transformers used in switching DC power supplies can be troublesome to wind.
Switching power supplies are relatively lightweight and small in size. Switching power supply is through the switching tube open and close the number of times or time, to regulate the output power, the efficiency is higher than the line The efficiency of switching power supply is higher than linear regulated power supply, the heat generation is relatively smaller, but the dynamic response is poorer, suitable for more stable load place. Switching power supply filter capacitor due to the working frequency The filter capacitor of the switching power supply has a very high frequency, so it has a great interference to the power grid.
DC linear regulated power supply is relatively heavy, the filter capacitor is large, the overall volume is large. DC linear regulated power supply is adjusting tube voltage divider to make the output voltage lower, so the burden of adjusting tube is very heavy. Adjustment tube burden is very heavy, large heat and low efficiency. But the dynamic response is very good, suitable for frequent load changes, such as audio amplifiers.
